So as to improve the quality of indoor air, generally, deodorization or dust collection is conducted by means of negative ion air purifiers or electric dust collectors, and recently, heat recovery ventilators, which serve as indoor and outdoor air ventilation systems allowing for the loss of indoor heat energy, have been introduced. The heat recovery ventilators are classified into duct type ceiling mounted ventilators, ductless floor mounted ventilators, and window mounted ventilators.
Among them, the duct type ceiling mounted heat recovery ventilators cause large amount of fan motor power consumption due to the generation of static pressure from the duct and need a relatively high installation cost. Accordingly, compact and slim type heat recovery ventilators, which can be installed on windows or window frames, have been recently proposed. The heat recovery ventilator largely includes a total heat exchange element for exchanging the total heat between indoor air and outdoor air and supply and exhaust means like an exhaust blower for exhausting the indoor air and a supply blower for supplying the outdoor air. In this case, a blower type supply and exhaust means having low noise is generally adopted in the compact and slim type heat recovery ventilator.
When the heat recovery ventilator does not operate, by the way, a damper is generally mounted on the supply and exhaust grills to block the indoor and outdoor air, and in this case, it is actually hard to apply the damper to the compact and slim type heat recovery ventilators.